1. Field of the Invention
The present invention relates to hinge assemblies and, particularly, to a hinge assembly for foldable electronic devices, such as mobile telephones, electronic notebooks, and so on.
2. Discussion of the Related Art
With the development of the technologies of wireless communication and information processing, portable electronic devices such as mobile telephones and electronic notebooks are now in widespread use. These electronic devices enable consumers to enjoy the convenience of high technology services anytime and anywhere. Consumers particularly favor foldable electronic devices for their convenience.
Generally, foldable electronic devices have most of the electronics in one housing, called the body. The other housing, called the cover, normally contains fewer electronic components than the body. Some foldable electronic devices, in fact, have all the electronics in the body, with the cover containing no electronics. Various types of hinge assemblies are used to join a body and a cover of a foldable electronic device, so that the cover can be selectably folded and unfolded relative to the body. Manufacturers are constantly seeking to reduce the volume, size, and/or weight of portable foldable electronic devices.
Thus, it is desirable that the hinge assembly coupling the main housing with the cover is modularized and miniaturized. A modularized hinge assembly has moving parts such as a cam member, a cam follower, and a spring, all held together in a unified structure. The structure is easily and quickly attached to the main housing and the cover during mass production. A miniaturized hinge assembly has as few parts as possible, with the parts being as small as practicable.
One kind of a hinge assembly is described in P.R. China Patent No. 98109390.6, issued on Aug. 28, 2002. The hinge assembly includes a shaft, a cam, a sliding cam, a spring, and an E-clip. The shaft has a securing portion at one end thereof, for engaging with a main body of a mobile phone. The cam defines a groove, for engaging with a flip cover of the mobile phone. The spring, the sliding cam, and the cam are located around the shaft, in that order. The sliding cam and the cam engage with each other, and the sliding cam can move along the shaft. The E-clip resists the cam, thereby preventing the cam from falling from the shaft.
Although the above-described hinge assembly is suitable for some foldable electronic devices, the cam, engaging with the flip cover, and the securing portion of the shaft, engaging with the main body, are respectively disposed at two ends of the hinge assembly, which makes the hinge assembly endure a relatively large torsion force. This need for such a substantial torsion force wastes energy, in the form of friction, and that friction causes abrasion of the spring and the shaft. That abrasion may eventually lead to premature malfunction or failure of the hinge assembly.
What is needed, therefore, is a hinge assembly which can have a relatively long working lifetime and which is energy efficient (i.e., easily opened) and convenient to use.